<span>7 electrons in each outer shell
Group 17
Most reactive
Fluorine, Chlorine, Bromine, Iodine, Astatine
Alkali Metals:
1 electron is each outer shell
Group 1
Also reactive, but not as much as the halogens
Lithium, Sodium, Potassium, Rubidium, Cesium, Francium </span>
The build up in the child's ear prevent sound from reaching the eardrum.
